#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
#define int long long
#define pii pair<int, int>
#define all(a) a.begin(), a.end()
using namespace std;
using namespace __gnu_pbds;
using ordered_set = tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update>;


int INF = 1e18; 
const int MOD = 998244353;
const int N = 5e5 + 10;
const int LOG = 20;
const int dx[4] = {0, 0, 1, -1};
const int dy[4] = {1, -1, 0, 0};

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int BIT[N], cBIT[N], a[N];
vector<int> nums;
ordered_set s;
int n, k;


void add(int x, int val, int c){
    for(int i = x; i <= nums.size(); i += i&-i){
        BIT[i] += val, cBIT[i] += c;
    }
}

int qry(int x){
    int res = 0;
    for(int i = x; i > 0; i -= i&-i) res += BIT[i];
    return res;
}
    
int cqry(int x){
    int res = 0;
    for(int i = x; i > 0; i -= i&-i) res += cBIT[i];
    return res;
}


int find(int x){
    int res = lower_bound(all(nums), x) - nums.begin();
    if(nums[res] == x) res++;
    return res;
}

int cal(int x, int l){
    int l_c = cqry(find(x));
    int r_c = l - l_c;
    int l_sum = qry(find(x));
    int r_sum = qry(nums.size()) - l_sum;

    return  l_c * x - l_sum + r_sum - r_c * x;
}

int f(int l){
    int mx = s.rbegin()->first, mn = s.begin()->first;
    int i = mn;

    for(int j = mx - mn; j > 0; j /= 2){
        while(i + j <= mx && i + j - 1 >= mn && cal(i + j, l) <= cal(i + j - 1, l)) i += j;
    }
    
    return cal(i, l);
};

// 0 1 2 3 4

void solve(){
    cin >> n >> k;    
    nums.clear();
    nums.push_back(0);
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        a[i] -= i;
        if(a[i] < 0) a[i] = -a[i];
        nums.push_back(a[i]);
    }

    sort(all(nums));
    nums.erase(unique(all(nums)), nums.end());

    int l = 1, r = 1;
    int ans = 0;

    while(r <= n){
        add(find(a[r]), a[r], 1);
        s.insert({a[r], r});

        while(l < r && f(r - l + 1) > k){
            add(find(a[l]), -a[l], -1);
            s.erase({a[l], l});
            l++;
        }

        ans = max(ans, r - l + 1);
        r++;
    }

    while(l <= n){
        add(find(a[l]), -a[l], -1);
        s.erase({a[l], l});
        l++;
    }

    cout << ans << '\n';
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int tt;
    cin >> tt;

    while(tt--){
        solve();
    }
}